South Grade Road, the stretch of San Diego County Route S6 going from State Route 76 to the summit, is popular among sport bike riders and sports car drivers due to its challenging nature (over 20 hairpin turns over the distance of less than ) and low traffic on most weekdays. Popularity and difficulty of the road is such that, on a typical warm-weather weekend, an average of two motorcycle crashes requiring medical attention occur in the area.
At the base of Palomar Mountain on S6 is Oak Knoll Campground, formerly known as Palomar Gardens. Palomar Gardens was made somewhat famous by an earlier resident George Adamski. Adamski had an observatory at Palomar Gardens and photographed objects in the night sky that he claimed were UFOs. Adamski co-authored Flying Saucers Have Landed in 1953, about his alien encounter experiences. Doane Valley, located within the State Park, is home to the Palomar Outdoor School for 6th grade students in the San Diego Unified School District.